2) Writes count characters to the output sequence from the character array whose first element is pointed to by s. The characters are written as if by repeated calls to sputc(). Writing stops when either count characters are written or a call to sputc() would have returned Traits::eof().

If the put area becomes full (pptr()== epptr()), this function may call overflow(), or achieve the effect of calling overflow() by some other, unspecified, means.